As is known in the art, the visual perception of a white substance can be altered through the deposition of a blue pigment and/or a blue dye. This effect is commonly used in laundry detergent products to make white clothes appear “whiter” to the human eye. This effect has also been applied to oral care products (e.g., toothpastes). For example, the blue dye and/or the blue pigment added to the oral care products may be deposited onto teeth, thereby allowing the off-white and/or yellow color of the teeth to appear whiter to the human eye.
While these oral care products provide effective whitening after only a single use, the blue dye and/or the blue pigment may only remain deposited on the teeth for a limited duration, thereby allowing the yellow stains to eventually reappear. Increasing the relative concentration of blue dye and/or blue pigment delivered to the teeth may increase the duration of deposition on the teeth and/or improve the perceived whiteness of the teeth. Accordingly, improved oral care compositions and methods for increasing the relative concentration of blue dye and/or blue pigment delivered to the teeth are desired.